Scrapy is a powerful tool that allows you to extract data from a wide variety of websites using a single command-line script. It also provides a simple way to export the scraped data in various formats, which can be useful for importing into programs.
How to use Scrapy
As we all know, the internet is a vast place with many websites and pages. This makes it difficult to find a “one-size-fits-all” approach to web scraping. It is common to take ad hoc approaches and end up writing code for every little task you want to perform.
Fortunately, there are several tools that make it possible to extract data from web pages with minimal effort and in an organized fashion. One such framework is called Scrapy, which can be downloaded and installed for free on your computer.
How to start a Scrapy project
To get started with Scrapy, you need to create an empty Python project and install the required libraries. Once you’ve got everything ready, you can start a scraping project by opening the file src/scrapy/scrap_project.py in your Python IDE.
How to crawl a website
The first step in building a Scrapy spider is to define its URLs and rules. The urls are the links that your spider will follow, and the rules are the classes that will tell it how to process each of them.
Once the URLs and rules are defined, you can create a new spider and open it for scrapping. When the spider is opened, scrapy laval will call the start_requests method. This method will convert each of the urls into requests and then run it against your rules to get scraped data following each request.
How to scrape more than one page
Another important feature of Scrapy is the ability to crawl multiple pages in parallel. This can save you a lot of time, especially when you are performing a large number of web crawls at the same time.
This can help you to achieve a much faster crawl than simply downloading all the pages at once. It is also an effective technique to speed up the processing of pages that are already cached, which can improve the overall performance of your spider.
How to export the scraped data
In addition to enabling you to scrape websites in a single line of code, Scrapy also provides a nifty little feature that allows you to export your scraped data in various formats such as JSON, CSV, and XML. The FEED_FORMAT and FEED_URI parameters can be used to specify the formats that your feed will contain, as well as the location where your exported files should be stored.
How to pause and resume crawls for large spiders
When performing a large amount of scraping, it’s often necessary to pause and resume your spiders as they crawl. This is particularly true when you are doing a broad scrape of thousands of domains at once. This is because the asynchronous architecture of Scrapy can be taxing on CPU and memory, even for small spiders.